Very easy to use, makes misalignment obvious instantly. I find it much simpler to use than any Cheshire or combination eyepiece with crosshairs.
If the primary mirror is centre marked then it's a doddle. I'd note that the hole on the cap is slightly off centre yet no matter how I turn it in the focuser the 'off centre' reflection stays within the centre mark of the primary mirror so it works fine for me.

Should have had one of these in my astro toolkit years ago. Cheap, effective and highly accurate. Easy to use with full instructions. At last, something to rely on that can be completed within less than a minute. The results from my F5 speak for themselves. Great bit of kit FLO, delivered on time with the usual gold standard of service.

Cheap, easy to use and very effective. My new scope needed a slight adjustment which only took a couple of minutes with this collimation cap. Highly recommended.

Simplicity itself. Having tried the laser tool that turned out to be useless as couldn't collimate that tool ad incoherent light I tried the Cheshire tool. Having looked at a useful YouTube item on collimation discovered the Collimation cap. After receiving this tool I was able to accurately collimate my reflecting telescope in minutes. So much value in a modestly priced tool.

Simple and easy to use collimation cap, saves making your own and this comes with very good reflective underside to make collimation alignment easy in mirrors. I use this for very quick check before each viewing session -

I'm new to astronomy so finding out that my newtonian needed collimating at first frightened me, so after much research I discovered a laser collimator and paid a small fortune for it and it just complicated maters, so looking for a simpler answer to collimation I came across the Rigel Aline and was surprised on exactly how simple it was to use and the results were fantastic and at a tenth of the cost of the laser.
I couldn't recommend the Rigel Aline enough

i lived in fear of collimation , then i bought a collimation cap, so straight forward to use, i highly recommend this cap.

I have a premium Premium Cheshire also, but this thing is actually better at a 6th of the price for quick collimation. I use it on a Sky-watcher 200p Dob, and all that is required (once you have your secondary square) is to point it at some blue sky and make sure the cycles are concentric.
Love it!

I haven't used this yet as the secondary on my scope is still aligned (the primary is non-collimatable) - but in terms of price and delivery then FLO have once again been unbeatable.

Brought this with my new 130pds skywatcher it works wonders keeping both secondary and primary mirrors aligned. The scope was well collimated as you would expect from FLO but while in use and transporting the gear it affects the alignment of the mirrors this is a must a great tool to use.